Business, science and entertainment applications depend upon computers to process and record data, often with large volumes of the data being stored or transferred to nonvolatile storage media, such as magnetic discs, magnetic tape cartridges, optical disk cartridges, floppy diskettes, or floptical diskettes. Typically, magnetic tape is the most economical means of storing or archiving the data. Storage technology is continually pushed to increase storage capacity and storage reliability. Improvement in data storage densities in magnetic storage media, for example, has resulted from improved medium materials, improved error correction techniques and decreased areal bit sizes. The data capacity of half-inch magnetic tape, for example, is now measured in hundreds of gigabytes on 512 or more data tracks.
A magnetic tape is typically a multilayer structure including a base layer and a magnetically definable layer in which data is stored. The magnetically definable layer may include pure metal particles that define the magnetic transitions that represent data. In other magnetic tapes, the magnetic layers may be either sputtered or evaporated magnetic films. In addition, the tapes may contain binders, lubricants and other materials.
One problem frequently encountered during reading and writing to tape is that magnetic materials or fragments therefrom can come loose from the tape and adhere to the head, sometimes leading to the formation of metallic bridges on the head. Another problem is formation of metallic bridges via electrostatic or electrochemical interaction between head and tape. Read sensors are particularly susceptible to failure due to shield-shorting as a result of bridging. Conductive accumulation have been found to be more prevalent in low humidify conditions, e.g., less than about 20% relative humidity. Such low humidity conditions are typical with the current prevalence of air conditioned server rooms and business places.
Accordingly, having some amount of hydration in the tape pack is desirable for promoting oxidation of metallic accumulations on the head.
However, at the other extreme, operating in a high humidity environment, e.g., typically greater than about 55% relative humidity, is problematic in that the tape may become too hydrated. This water in turn is implicated in corrosion of corrodible materials in the head, such as the iron in the writer pole tips. In addition, aluminum oxide, which is a typical component in modern heads, is amphitheric and susceptible to chemical attack when subjected to a hydrated environment. It is found that excessive tape hydration accelerates head erosion. Further, excessive hydration is widely believed to increase stiction between the tape and the head.
The only known solutions to these problems are to bury the reader and writer structures to prevent contact with the water or the conductive accumulation, and/or to coat the head with a durable wear coating. In the former case, such a recessed sensor has not been implemented and is believed to be difficult to manufacture, and would also result in an undesirable spacing loss. The latter method is complex and expensive and the coatings may wear off over time, even with pre-recession.